In recent years there has been an increasing use of positive displacement fluid infusion pumping devices for delivery of fluids intravenously or intra-arterially to patients in hospitals or other patient care locations. These have, to a great extent, replaced the time honored gravity flow control systems, primarily due to their much greater accuracy and delivery rates and dosages, relative sophistication in permitting a flexible and controlled feed from multiple liquid sources and particularly their ability to control with precision the amount of potent drugs delivered to the patient over a given period of time.
A typical positive displacement infusion pump includes a pump driver device and a disposable cassette. The disposable cassette, which is adapted to be used only for a single patient and for one drug delivery cycle, is typically a small plastic unit having one or more inlets and an outlet respectively connected through flexible tubing to the fluid supply containers and into the patient receiving the infusion. The cassette includes a pumping chamber with a flow of fluid through the chamber being controlled by a plunger or piston activated in a controlled manner by the driver device.
For example, the cassette chamber may have one wall thereof formed by a flexible diaphragm which is reciprocated by the plunger in the driver to cause fluid to flow. The pump driver device includes the plunger/piston for controlling the flow of fluid into and out of the pumping chamber in the cassette, and also includes control mechanisms to assure that the fluid is delivered to the patient at a preset rate, in a predetermined manner, and only for a particular pre-selected time or total dosage. The pump driver device may also include pressure sensing and other liquid flow monitoring devices as well as valving members for opening and closing various passages in the cassette including the inlet and outlet passages of the pumping chamber.
It is envisioned that such displacement infusion pump system may be modified to include a microprocessor capable of driving several different drug infusion programs, each program requiring a different type medicant. It may also be desirable to include an infusion program for the pump capable of delivering a nutrient to the patient. Clearly, each type of medicant delivered would require a different protocol, including delivery rate, drug mixing, timed delivery, bolus delivery, etc. These are only a few of the drug or nutrient parameters to be considered.
Thus, it can be readily recognized that even if a multi-program drug infusion pump were available, not all programs available in the pump would operate as efficiently if the pump employed a cassette of a single type. Substantial efficiencies of usage and drug and/or nutrient delivery would result if such a multi-program infusion pump could accept and use cassettes of varying types, each type cassette received by the pump to be compatible with a specific program stored in the pump for actuation by the pump microprocessor.
Different types of disposable cassettes may be used, i.e., special purpose cassettes such as enteral pump cassettes, pediatric cassettes, patient controlled analgesia cassettes, or automated drug infusion cassettes, to give the drug infusion pumping system the broadest possible range of uses. However, the use of the wrong cassette for a particular application may be undesirable, or even dangerous, so that it would be desirable to provide means to identify the particular type cassette installed on the pump.